Facebook is the entity creating this work, and is the root of the problem (by contracting a 3rd party to perform work that they very well understand the consequences of). The article is suggesting that Facebook should be held accountable for the detriment (trauma) that their work is causing. I think the article even argues that the contractors aren't equipped to deal with a problem of this magnitude/seriousness. Facebook is in the best position to rectify their moral accounts, but we all know that's not going to happen because they are evil and so forth.